Improvement in the manufacture of boilers, steam-cylinders, fittings



, GEoRGE w. BOLLMAN. u Improvement in Manufacture of Boilers, SteamCylinders, and Flttmgs.

No. 120,235, Parentedom, 24,1871.

PATENT OEEIoE.

GEORGE W. BOLLMAN, OF PITTSBURG, PENNSYLVANIA.

IMPROVEMENT IN THE MANUFACTUTIE 0F BUILERS, STEAM-CYLINDEHS, FITTINGS,&c.

Specification forming part of Letters Patent No. 120,235, dated October24, 1871.

To all whom t may concern:

Beit known that l, GEORGE W. BOLLMAN, of Pittsburg, in the county ofAllegheny and State of Pennsylvania, have invented a new and use'- fulImprovement in Manufacture of Boilers and Fittings; and I do herebydeclare the following to be a full, clear, and exact descriptionthereof, reference being had to the accompanying drawing forming part ofthis specica-tion, in Which- Figure l is a view of a portion of asteam-boiler patented in Letters Patent No. 107,181. Fig. 2 is a view ofa steam-cylinder; and Figs. 3, 4, 5, 6, and 7 are views of gas andwater-pipe fittings.

In the manufacture of gas and water-fittings, tubular boilers, andsteam-cylinders heretofore a soft iron has been used, because the hardervarieties are very expensive to bore out and finish, the grain being toocoarse and hard. rIhe soft iron, although easy to cut, is notsusceptible of a high finish, and Yis otherwise not suitable for thepurpose, being somewhat porous in its texture.

By experiment I have discovered that iron and steel combined in acertain proportion give a metal of a superior toughness and of a closergrain than cast-iron, and which is susceptible of a fine finish, andaffords a better surface for cutting screw-threads. The amount of steelI combine with a given quantity of iron is from ten to fifteen per cent.of the whole quantity. The iron and steel are melted together inafurnace of the ordinary construction, and the casting done in the usualway. For this purpose I generally use a low grade of lsteel--scrapsteelor carbonized ironalthough any kind may be used. The proportions givenmay be varied somewhat, depending on the quantity of iron and steelused. If a greater hardness is required the quantity of steel isincreased.

Vhat I claim as my invention, and desire to secure by Letters Patent,is-

The manufacture of steam-boilers, cylinders, and fittings from a mixtureof cast-iron and steel or carbonized iron, substantially as herenbeforedescribed.

In testimony whereof I, the said GEORGE W. BOL'LMAN, have hereunto setmy hand.

. GEORGE W. BOLLMAN.

Witnesses:

JOHN A. FLOYD, JAMES I. KAY. (85)

